A wired local area network is typically a broadcast network where data transmitted from a node can be received by all the other nodes. The respective nodes over the network share a channel, thus posing a tremendous hidden trouble of security to the network. An attacker can capture all data packets over the network simply by accessing and listening to the network. A Local Area Network (LAN) defined in the existing national standard GB/T 15629.3 (corresponding IEEE 802.3 or ISO/IEC 8802-3) has no data secure method available, so that the attacker may steal crucial information easily.
In the wired local area network, the IEEE secures the link layer by enhancing the security of the IEEE 802.3. The IEEE 802.1AE provides a data encryption protocol to protect the Ethernet and takes a security measure with hop-by-hop encryption to secure a delivery of data between the nodes of the network. This security measure brings a considerable calculation load on a switching device in the local area network, thus easily resulting in an attack of the attacker to the switching device; and also a data packet will be transported from a transmission source node to a destination node with a larger delay, thus lowering the efficiency of transmission over the network.
A topology of the wired local area network is relatively complex and also involves a large number of nodes (here a terminal and a switching device are referred collectively to as a node), so data communication in the network is relatively complex. If a shared key is created between every two nodes, then the nodes have to store a relatively large number of shared keys; and if a shared key between adjacent nodes is used with the security measure with hop-by-hop encryption, then the switching device of the network may suffer from a considerable calculation load.
Therefore it is desired to study a method to address the issue of secure communication between nodes, thereby ensuring secure transmission of data between nodes on one hand and lowering the number of keys and the complexity of creating a key as much as possible on the other hand while taking a encryption and decryption capability of a node into account.